LPC Microcontrollers中的主题 Re: LPC55S16 RAM entries after software reset

LPC55S16 RAM entries after software reset

steffenrose — Wed, 04 Aug 2021 16:34:20 GMT

Hello,

I want to create a unsecure secondary bootloader and want to save some byte between software reset. It seams that the location 0x20000000..0x20010000 is changed during this reset. I stoped in ResetISR() and the Debugger show different values. So it is not the clib, that initialize the data. It seams the LPC internal bootloader.

The reset is NVIC_SystemReset().

Is there a location, where I can use some Bytes that do note change? At the best a location for the hole LPC55xx family.

I use the MCU xpresso IDE and the LPC55S16-EVK at the moment. I checked the memory using the Memory window of the IDE.

Re: LPC55S16 RAM entries after software reset

Alice_Yang — Thu, 05 Aug 2021 02:40:52 GMT

Hello steffenrose,

How about save your data in Flash memory?

Alice

Re: LPC55S16 RAM entries after software reset

steffenrose — Thu, 05 Aug 2021 07:26:38 GMT

It's short time data, that I want to use to configure the restarted device.

Re: LPC55S16 RAM entries after software reset

Alice_Yang — Fri, 06 Aug 2021 02:30:42 GMT

Hello steffenrose,

How about place the data in specific memory region, refer to MCUXpesso IDE User Guide:

Re: LPC55S16 RAM entries after software reset

steffenrose — Fri, 06 Aug 2021 10:51:04 GMT

Thank you very much. My question was related a specific memory location. Now I learnd, that the Boot Rom use a lot. This memory is not suitable to save values during a software reset,

I think the MCUXpresso autogenerated linker scripts should prevent this location to use for the noinit sections.

Currently I use a different way.
I set a offset for the Stack location and create a section at the end using

--section-start=command=0x2000FFF0

Thats why I want, that our end customer can use the Managed linker scripts for different derivates.

Unattractive is, that objcopy use it for ihex and binary generation like the text section.

Sections: Idx Name Size VMA LMA File off Algn 0 .sec1 00008000 00008000 00008000 00000000 2**0 CONTENTS, ALLOC, LOAD 1 .sec2 00007770 00010000 00010000 00016811 2**0 CONTENTS, ALLOC, LOAD 2 .sec3 00000010 2000fff0 2000fff0 0002b82b 2**0 CONTENTS, ALLOC, LOAD

Re: LPC55S16 RAM entries after software reset

Alice_Yang — Tue, 10 Aug 2021 03:27:41 GMT

Hello steffenrose,

Thanks for your sharing, I will take a ticket to MCUXpresso development team about your this suggestion:" I think the MCUXpresso autogenerated linker scripts should prevent this location to use for the noinit sections."

Alice